全文获取类型
收费全文 | 151篇 |
免费 | 5篇 |
专业分类
化学 | 99篇 |
力学 | 4篇 |
数学 | 23篇 |
物理学 | 30篇 |
出版年
2022年 | 1篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2017年 | 2篇 |
2015年 | 5篇 |
2012年 | 12篇 |
2011年 | 10篇 |
2010年 | 8篇 |
2009年 | 4篇 |
2008年 | 8篇 |
2007年 | 5篇 |
2006年 | 8篇 |
2005年 | 11篇 |
2004年 | 5篇 |
2003年 | 6篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1992年 | 3篇 |
1985年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1968年 | 4篇 |
1966年 | 2篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1937年 | 2篇 |
1934年 | 1篇 |
1932年 | 3篇 |
1931年 | 1篇 |
1927年 | 1篇 |
排序方式: 共有156条查询结果,搜索用时 15 毫秒
61.
Radlinski AP Ioannidis MA Hinde AL Hainbuchner M Baron M Rauch H Kline SR 《Journal of colloid and interface science》2004,274(2):607-612
Backscatter SEM imaging and small-angle neutron scattering (SANS) data are combined within a statistical framework to quantify the microstructure of a porous solid in terms of a continuous pore-size distribution spanning over five orders of magnitude of length scale, from 10 A to 500 microm. The method is demonstrated on a sample of natural sandstone and the results are tested against mercury porosimetry (MP) and nuclear magnetic resonance (NMR) relaxation data. The rock microstructure is fractal (D=2.47) in the pore-size range 10 A-50 microm and Euclidean for larger length scales. The pore-size distribution is consistent with that determined by MP. The NMR data show a bimodal distribution of proton T(2) relaxation times, which is interpreted quantitatively using a model of relaxation in fractal pores. Pore-length scales derived from the NMR data are consistent with the geometrical parameters derived from both the SEM/SANS and MP data. The combined SANS/BSEM method furnishes new microstructural information that should facilitate the study of capillary phenomena in hydrocarbon reservoir rocks and other porous solids exhibiting broad pore-size distributions. 相似文献
62.
Epoxy-1,1,2-triehloroethane (1) was synthesized by the autuoxidation of trichloroethylene and was characterized. It was shown to react readily with 2-mercaptobenzirnidazole (2), 1 -melhyl-2-mercaptoimidazole ( 3 ), p-nitrolhiophenol ( 4 ), and 3,4-dichlorolhiophenol ( 5 ) forming 2-chloro-2-(benzirnidazole-2-thio)acelie acid ( 6 ), 2-ehloro-2-(1-methylirnidazole-2-thio)aeetic acid (characterized as methyl ester ( 8 )), 2-chloro-2-(4-nitrolhiothiophenoxy)-4-nilrophenylthioaeetate (9), and 2-chloro-2-(3,4-dichlorothiophenoxy)-3,4-dichlorophenylthioaeetale ( 10 ), respectively. Base hydrolysis of 9 yielded 2,2-di(4-nilrothiophenoxy)acetie acid ( 11 ). Adducl 9 decomposed on silica gel yielding p-nitrophcnyldisulfide ( 12 ). 相似文献
63.
The effect of γ-irradiation and post-irradiation heat treatment on the specific volume versus temperature relationships of polytetrafluoroethylene (PTFE) samples (1/2-in. diameter rods) have been studied over the 40–150°C. temperature range for radiation doses up to 8.9 X 108 rad. At low doses the specific volume at any temperature decreased with dose, but above about 108 rad it increased with dose. Similarly, the rate of volumetric expansion initially decreased with dose, while, at very high doses (8.9 X 108 rad) the rate of expansion at temperatures above 100°C. exceeded that of the unirradiated PTFE. Heating at 150°C. for 100 hr. produced a substantial decrease in the specific volume and a decrease in the rate of expansion for the irradiated samples. Irradiation effects in PTFE are considered to be a result of such factors as radiation-induced chain scission, increased crystallinity, and increased void content. Changes resulting from post-irradiation heat treatment can be attributed to increased crystallinity, decreased void content, and weight loss. 相似文献
64.
Biggs S Kline SR Walker LM 《Langmuir : the ACS journal of surfaces and colloids》2004,20(4):1085-1094
Solutions of rodlike polymeric micellar aggregates, formed from the polymerization of cetyltrimethyl-ammonium 4-vinylbenzoate (CTVB), adsorb at the solid-liquid interface. The poly-CTVB aggregates are imaged in situ using soft contact atomic force microscopy. The aggregates form self-organized two-dimensional films that show a high degree of order on nanometer to micrometer length scales. Unlike their simple surfactant analogues, the adsorbed layer structures are permanently adsorbed and the structure is resilient to washing with pure solvent. In the case of poly-CTVB, the adsorbed aggregates appear to be rigid cylindrical structures of between 30 and 60 nm in length. At the interface, the center to center spacing of the aligned aggregates is 8+/-1 nm. Images of a second series ofpolymerized aggregates formed by the copolymerization of CTVB with sodium vinyltosylate revealed a change in the aggregate structure to a set of linked spherical aggregates. These polymerized aggregates also spontaneously form a permanent adsorbed layer at the solid-liquid interface. 相似文献
65.
66.
The ?-X electronic absorption spectrum of propargyl peroxy radical has been recorded at room temperature by cavity ring-down spectroscopy. Electronic structure calculations predict two isomeric forms, acetylenic and allenic, with two stable conformers for each. The acetylenic trans conformer, with a band origin at 7631.8 ± 0.1 cm(-1), is definitively assigned on the basis of ab initio calculations and rotational simulations, and possible assignments for the acetylenic gauche and allenic trans forms are given. A fourth form, allenic cis, is not observed. Simulations based on calculated torsional potentials predict that the allenic trans form will have a long, poorly resolved progression in the OOCC torsional vibration, consistent with experimental observations. 相似文献
67.
68.
Kline TR Iwata J Lammert PE Mallouk TE Sen A Velegol D 《The journal of physical chemistry. B》2006,110(48):24513-24521
We recently reported the convection and pattern formation of tracers caused by a catalytically generated electric field. The electric field arises due to the heterogeneous electrochemical reduction and oxidation of hydrogen peroxide (H2O2) on silver (Ag) and gold (Au), respectively.1 Here we describe an electrokinetic model, developed in conjunction with experiments, that explains the details of the convection and pattern formation phenomenon. The model also enables the measurement of reaction kinetic parameters that are otherwise difficult to obtain. This quantitative model serves as a platform for the modeling of other catalytic redox systems and systems with broken symmetries. 相似文献
69.
Marijke WA de Backer Carlos P Fitzsimons Maike AD Brans Mieneke CM Luijendijk Keith M Garner Erno Vreugdenhil Roger AH Adan 《BMC neuroscience》2010,11(1):81
Background
This study compared the transduction efficiencies of an adeno-associated viral (AAV) vector, which was pseudotyped with an AAV1 capsid and encoded the green fluorescent protein (GFP), with a lentiviral (LV) vector, which was pseudotyped with a VSV-G envelop and encoded the discosoma red fluorescent protein (dsRed), to investigate which viral vector transduced the lateral hypothalamus or the amygdala more efficiently. The LV-dsRed and AAV1-GFP vector were mixed and injected into the lateral hypothalamus or into the amygdala of adult rats. The titers that were injected were 1 × 108 or 1 × 109 genomic copies of AAV1-GFP and 1 × 105 transducing units of LV-dsRed. 相似文献70.
J. van der Lee W. M. Clark L. Kline J. E. Marsh R. de Jersey Fleming-Struthers H. Leffmann Ch. C. Pines B. T. Effinger H. J. Schaeffer F. A. Faught M. Krajĉinović C. A. Adams J. R. Nicholls J. Penzoldt G. Denigés D. D. van Slyke P. Fleury Y. Awad A. Meyer Suzanne Mathey 《Analytical and bioanalytical chemistry》1932,89(9-10):367-371